The present invention relates to a method for the manufacture of a device ensuring an electrical and thermal contact between a plurality of metal surfaces. It also relates to the device obtained by this method and the use of said device, particularly in the microwaves field.
It is known from the prior art to provide an electrical and thermal contact between two metal surfaces, which can for example be the surfaces of two coaxial cylinders constituting two connections of a microwave electronic tube of coaxial geometry, such as power tetrodes and triodes, using flexible strips. These strips are cut from sheets of a metal having a coefficient of elasticity, followed by bending and optionally thermal treatment. This is for example the case when using beryllium bronze strips, whose elasticity is increased by the heat treatment. These strips are then welded to one of the surfaces, generally in a groove hollowed out of said surface and which serves to retain the weld. The other surface is then placed in contact with the strips, so that an electrical and thermal contact is produced between the two metal surfaces.
However, contact by flexible strips has numerous disadvantages and reference is made to certain of these below:
The large contact surface between each strip and the facing surface and the displacement of the contact points from one strip to the next, which can lead to the creation of electrical arcs between the strips.
The fragility of these strips which are damaged if subject to sliding orthogonal to their bending direction and which consequently do not make it possible to obtain a contact between two surfaces subject both to rotary and translation movements.
Manufacturing difficulties, because it is necessary to take numerous precautions when welding the strips in order to ensure that they do not lose their elasticity and their protective coating.
Its too compact structure (the strips generally have a width of two to three millimeters and are only separated by a gap of approximately one millimeter), so that the ventilation of the contact is difficult and requires the use of very powerful fans.
It is also known from the prior art to provide an electrical and thermal contact between two metal surfaces by using a spring positioned in a groove hollowed out of one of the surfaces and held at the bottom of the groove by an elastic link. The other surface is then brought into contact with the spring, so that an electrical and thermal contact is provided between the two metal surfaces.
Compared with contact by flexible strips contact by a spring has the advantage of being punctiform and not requiring welding and in addition its ventilation is easy, because it is formed from wire and not metal sheets. However, contact by a spring has the serious disadvantage of its fragility. Thus, it is easily damaged, particularly during its installation and the turns do not remain uniformly spaced. Thus, like contact by flexible strips contact by spring does not make it possible to bring about a contact between two surfaces subject both to rotary and translation movements.